Pilots of a U.S.-contracted de Havilland DHC-8-202 'Prospector' are faulted in an Oct. 5 crash over Panama that killed an Air National Guardsman and three others. (Air Force)

The failure of contracted pilots to keep their aircraft over water during an Oct. 5 night flight over Panama led to a crash that killed an Air National Guard member and three other crew members, according to an Air Combat Command-directed Accident Investigation Board report released Wednesday. The two pilots survived.

Master Sgt. Martin Gonzales, 39, and the others, unnamed in the report, were aboard a U.S.-contracted de Havilland DHC-8-202 “Prospector” on a surveillance mission tracking drug traffickers.

While the main cause of the crash was the failure to keep the aircraft flying over water, major contributory causes were the pilots’ inappropriately delegating terrain avoidance responsibility, ineffective communication, and an inoperative ground proximity warning system, which, had it functioned, would have given the pilots ample time to avoid the ground, the report states.

Additionally, increased oversight by U.S. Southern Command could have helped the crew avoid the crash.

“While operational oversight alone may not have prevented the mishap, it is clear the lack of such oversight negatively affected safety,” AIB President Brig. Gen. Scott Zobrist said in the report. “I find by a preponderance of the evidence that lack of operational oversight led to inadequate aircrew training and unsafe maintenance practices, which substantially contributed to the mishap.”

The aircraft and surveillance payload was destroyed at a loss of about $7.2 million.

On Oct. 4, the Joint Interagency Task Force South tasked the crew to fly a night-time detection and monitoring operation in the Caribbean Sea off the coast near the Colombian border, helping the Colombian Navy and law enforcement track suspected drug trafficker ships.

The aircraft was piloted by two Sierra Nevada Corp. pilots, one of whom had no recent flying hours in the aircraft, according to the report. Gonzales was on board as an escort for a lieutenant in Panama’s Air and Naval Service. Riding with them in the back of the plane was a mission commander, an Air Force veteran who had previously worked with U.S. Customs and Border Protection.

The aircraft’s Enhanced Ground Proximity Warning System was turned off, the report states, because it had been producing errant warnings during previous flights. However, pre-flight checklists did not account for the disabled systems, even though Federal Aviation Administration rules state that aircraft can only fly with a disabled system if “alternate procedures are established and used,” the report states.

“However, alternate procedures were not established or discussed by the [crew], other than [the second pilot] stating they needed to ‘stay off the land,’ ” the report states.

The aircraft took off at about 10:45 p.m. local time and headed out to sea, where it was intended to stay. The aircraft’s lack of advanced navigation systems, combined with the pilots not wearing night-vision goggles, meant visibility was limited and staying over water was safer than flying over the changing coastal landscape.

Shortly into the flight, the crew found a vessel and set up a surveillance orbit to feed information to Colombian law enforcement. While the crews in the cabin were tracking and radioing information, however, the pilots tasked them with using their equipment for duties normally handled by pilots, such as ground avoidance. The new duties made their workload almost “overwhelming,” the report states. Additionally, the crews were not clear on all of their navigational duties nor the best way to communicate them to the pilots, the report states.

“Inconsistent verbal communications resulted in pilot navigational confusion on multiple occasions during this phase of flight, as the mishap pilots depended on [the American crew members’] navigational directions,” the report states.

Shortly into flight, the aircraft began flying over land for the first time, for about one minute and 25 seconds. After correction, it returned to sea for multiple orbits.

At about 12:40 a.m., the aircraft once again flew over land. After about two miles inland, the pilot began to turn, heading due north.

During the turn, the cockpit voice recorder captured a “pull up” notification that was not from a ground collision avoidance system, and the pilots afterward said they had no recollection of it.

The aircraft began to climb, but by then, it was too late, the report states.

“OK, here we go, power,” the co-pilot said.

“Power up. Thanks,” the pilot said

“And go into a nice, steep climb,” the co-pilot responded. “Yep.”

Three seconds later, the radio cut out as the plane crashed into a hill, about 300 feet below the crest and 1 kilometer from the Panama-Colombia border.

The cabin was immediately engulfed in flames. The pilots, unable to use the emergency exit, jumped out of a window. The first pilot fell about 15 feet to the ground and injured himself. The co-pilot climbed down a tree as flames spread into the cockpit. The back exit was on fire, with the crew still inside.

“It was later determined by a review of autopsy evidence that any rescue attempts would have been futile because the four other aircrew members died upon impact,” the report states.

It took rescue crews about eight hours to find and rescue the surviving pilots and recover the remains of the crew. The pilots were taken to a hospital in Bogota, Colombia, and then back to the U.S. for care.

“Our hearts remain with the families of the men who lost their lives in this tragic crash,” Marine Gen. John Kelley, SOUTHCOM commander, said in a release following the crash. “It is a terrible tragedy, but we remain committed to finding out what happened and hopefully bring some sort of peace to the families.”

Immediately following the crash, Gonzales’ wife issued a statement through SOUTHCOM.

“The loss and pain of losing my husband, Master Sgt. Martin Gonzales, is indescribable. He passed away very tragically while proudly serving for the U.S. Air Force. He loved his job and was willing to risk his own life for others. He leaves behind two beautiful children, Nathan, 7, and Kaitlin, 4. This is a very difficult time for our family. I still can’t believe the plane my husband was in crashed and took his life. All I have left are memories of him. It’s difficult to know that I will never see or hear his voice again. To me, he is an American hero!”